• A New Solid-State Audio Power Amplifier Topology


    A new audio power amplifier topology is presented in this white paper. This new topology allows a power amplifier to be separated into two independent stages: voltage gain stage and current gain stage. These two stages can be optimized individually before they are put together to form a power amplifier. With the use of the current gain stage, a loudspeaker can be completely isolated from the voltage gain stage if no global feedback is chosen. Some details are given showing how a current gain stage is implemented by a buffer amplifier. The buffer amplifier does not require global feedback to bring the output to DC ground level. In addition, a DC blocking capacitor can be placed in the interface between the voltage gain stage and current gain stage instead right in the input. A smaller and better quality capacitor can be used. As a result, the performance of an audio power amplifier can be more easily to be optimized than conventional design.















  • Fully Balanced Hybrid Power Amplifier


    A fully balanced hybrid power amplifier contains of an voltage amplification stage by all vacuum tubes and a current amplification stage by solid-state semiconductor devices. The voltage amplification stage and the current amplification stage are configurated by the patented Dual Balanced Feedback Topology (DBFT) so that balanced signals are fully preserved. The current amplication stage is implemented by patented High Current Buffer Amplifier (HCBA). Two HCBAs are used per channel. One HCBA amplifies signal of one phase and the other HCBA amplifies signal of the opposite phase. Since all vacuum tubes are used for signal amplification, and the HCBAs have unity voltage gain, the overall sound has retained very much to what we expect from a tube power amplifier. But it has advantage over conventional vacuum tube power amplifier in terms of high current drive provided by the semiconductor buffer amplifier at the output.















  • Vacuum Tube Balanced Power Amplifier

    The patented Dual Balanced Feedback Topology (DBFT) can be easily applied to fully balanced vacuum tube audio power amplifiers. The DBFT can, first of all, completely get rid of a phase splitter which is, however, needed by all conventional push-pull type power amplifiers. Secondly, one pair of feedback is applied to the first and second stages of the power amplifier. Thus the two out-of-phase signals are accurately reproduced so that the fine musical details can be preserved. Thirdly, the second pair of feedback is applied to the overall amplifier. Hence the linearity of the power amplifier is further improved. Due to the balanced operation, common mode noises and distortions that are picked up by interconnect and loudspeaker cables can be effectively cancelled out. The result is a superb performance fully balanced vacuum tube audio power amplifier.